Recently, various mobile devices such as smartphones have been developed. These mobile devices comprise various functions, for example, a communication function and a position detection function.
Further, more recently, miniaturization of information equipment causes various wearable devices to be developed, and a market thereof is growing. A wearable device is an electronic apparatus which can be attached to a body of a user. The wearable device comprises a function of measuring, for example, number of steps, moving distance, calorie consumption, sleeping time, etc.
Some wearable devices do not comprise a display. Even if they comprise a display, the display may be small. Accordingly, data measured by the wearable devices is hard to confirm by the wearable devices.
To solve such a problem, data stored in a wearable device may be transferred to a mobile device by performing communication between the wearable device and the mobile device to confirm data measured by the wearable device using a display of the mobile device.
Since mobile devices which are portable devices may be lost or stolen, a service of backing up data accumulated in the mobile devices and measured by wearable devices in a backup server connected to a network has been considered.
Wearable devices are limited in size, and a large-capacity storage cannot be provided therein. Accordingly, after measured data is transmitted from a wearable device to a mobile device, the transmitted data is sometimes deleted from a storage of the wearable device.
At present, some users own a plurality of mobile devices. If, after measured data is transmitted from the wearable device (first wearable device) to a mobile device, measured data is transmitted from a wearable device to another mobile device (second mobile device), the data transmitted to the first mobile device cannot be confirmed in the second mobile device. Then, synchronization processing of data between the second mobile device and a backup server has been considered.
In the past, an effective synchronization method between a mobile device (electronic apparatus) and a backup server has not been considered.